Although breastfeeding is generally recognized as the optimal way to feed infants through the first 4-5 months, it is well known that many American women nurse their babies for much more limited periods or not at all. In this prospective study characteristics associated with choice and duration of breast feeding are being investigated. The specific objectives of the study are: (1) to provide detailed information on the change in the infant-feeding pattern over time; (2) to investigate the underlying meaning of the milk insufficiency syndrome; (3) to investigate the relation between maternal employment and choice and duration of breast feeding; (4) to determine the sociocultural differences in infant feeding between two ethnic groups. Approximately 1200 women having their first child in one of three hospitals in the Washington, DC, area were interviewed with respect to factors that may have influenced their plans for infant feeding. Data collection was completed in April, 1986, and data cleaning, editing and file building were completed in August, 1986.